On a rotating metal plate lighting gel is ignited, and then four upright glass plates are fixed around the flames. From the original height of 20cm, the flames grow into an impressive pillar of fire. Using a thermal imaging camera, it is shown that the sheets of glass heat up to different extents.
How does it work?
The warm combustion gases rise up and suck the air from outside over the top of the glass panes. The air which is sucked from the outside to the inside passes tangentially in line with the direction that the fire is rotating. The air rotates faster the further it is away from the centre of rotation (Pirouette Effect), and a tornado emerges. The high flow rate of air allows the tornado to reach up to 1.3m in height. The different temperatures of the glass panes can be explained by their different insulating properties. Two are made of just glass and two with double glazing (i.e. with an argon gas insulation layer in between).
Safety Tips
The lighting gel is a safety-gel which is Isopropanol based, and cannot get out of control. During combustion, no soot is produced. The flame cannot go horizontally past the glass panes and extends up to 30cm above their height. Should something unexpected happen, a cover can be immediately placed over the flames so they are quickly put out. The tornado should be placed on the floor, so the distance to the ceiling is as great as possible. If in doubt, we ask the local fire station to implement and accept the experiment.
